A Design Method of Disturbance Observer to Cope with Frequency Variation

Abstract

A well known control system which can reduce the adverse effect of a periodic disturbance with single frequency is the disturbance obsever. However, in many cases of industrial systems disturbance frequency is varied for some frequency range. Therefore, it may be difficult to reduce the adverse effect of the disturbance by the use of the traditional disturbance observer.
In this paper, a design method of new disturbance observer which can cope with the frequency variation is proposed. The main idea of this design method is to synthesize the disturbance observer as a gain-scheduled controller. The proposed disturbance observer is constructed as low degree and low gain controller with superior steadystate characteristic. As compared with the traditional disturbance observer and the H∞ controller, the usefulness of the proposed disturbance observer was shown by numerical simulations.